The main ingredients you will need are:
Google Keyboard or any other keyboard you like.
LMT Pie Launcher
NexMusic or your preferred player supported by Themer.
After you have downloaded the listed apps the first one you have to install is the keyboard you chose and enable it as default. This is because you will need to disable the nav bar and after you do the LG keyboard will force close. Then as mentioned you have to disable the nav bar using G2 TweaksBox> Miscellaneous> check the "disable nav bar" box but don't reboot. Before you reboot make sure you installed LMT Pie Launcher and checked the first two boxes (Activate service and Autostart service) on the app's settings.
Then reboot your device and once you do you won't have the nav bar anymore but now you can use the LMT pie launcher to navigate through the phone. It can be launched by swiping from the left, right and bottom of the screen to the center. It can also be completely customized but I'll explain that later.
After you have disabled the nav bar, have enabled a keyboard and LMT pie is working you can install Themer as a normal app from the Play Store, choose a theme and apply it. Themer was recently updated to support LG's default Music app but they don't seem to get along that well yet. That's why I suggested to use NexMusic which has given me the best experience and works great from the lock screen too. You can select it from the Themer app and after you download it, it will be set as default.
So basically after you've installed everything your phone should look something like this:
You can also customize the LMT pie and make it look similar to this:
LMT pie comes with a standard 5 buttons layout that should be enough to help you get through the setup process but if you want to customize it a little more you can go to the last section of LMT's settings, PIE, and there configure it button by button as well as the long press or even add a second line of buttons. The new custom buttons you choose will appear one by one as you select them. For customizing the color you can use a menu on the first section and there you can also raise the top radius, bottom radius and outline as well as many other features.
To add a lock/shutdown function you have to enable a custom key and set it to 26. That's the one that I have on the far left.
I started using it a couple days ago and haven't had any problem so far. The biggest loss you might get from disabling the nav bar is that you loose the option of using multi-window but I'm pretty sure there's a work around for enabling it on LMT; just haven't figured that out yet
Battery life is not affected at all and I can say it improved a bit on this specific theme I'm using because of the dark BG and UI. I wanted to share this because I really liked the way the G2 looks with Themer and also to start a discussion and see what new things I can learn from any of the apps I used.
Credit goes to all the developers of each and every app I mentioned so give your thanks to them and support their projects in any way possible. No need to leave thanks here, ideas and helpful discussions would be more appreciated.